India plans to cut its fertiliser subsidy bill by at least 15 percent for the fiscal year 2013-14, four sources told Reuters, a move that takes advantage of a fall in international prices to help narrow the country's fiscal deficit.

Fertilisers, after oil and food, account for the third-biggest share of India 's total subsidy bill, which is expected to rise to 2.4 percent of gross domestic product (GDP) in fiscal 2012/13.

The government had estimated the fertiliser subsidy at 609.7 billion rupees ($11.4 billion) for the fiscal year ending next month, but it is likely to be much higher than the target.

Based on the estimated subsidy level for 2012/13, a 15 percent cut would save the government nearly 91.5 billion rupees. Calculating from the projected fiscal deficit for this year, this would narrow the deficit by as much as 0.1-0.2 percentage point.

Finance Minister P. Chidambaram has staked his reputation on lowering the deficit to 5.3 percent of GDP to improve the investment climate following ratings agency threats to downgrade India 's sovereign debt to junk if action was not taken.

Reuters reported exclusively last week that, after small steps to reduce fuel subsidies, Chidambaram is now putting welfare, defence and road projects on the chopping block in a last-ditch attempt to hit his deficit target by next month.

A senior official at the fertiliser ministry with direct knowledge of the plan said the subsidy bill would be reduced by at least 15 percent or more in the next financial year, though the actual cut will depend on the views of the agriculture and finance ministries.

"Since international prices have fallen, obviously, (the) subsidy will go down," Junior Fertiliser Minister Srikant Jena told Reuters separately, adding that a final decision on the extent of the cut was yet to be taken.

The move is unlikely to trigger opposition from farmers as the government plans to leave unchanged the subsidy for urea, the most-used fertiliser, an official with a Mumbai-based state-run fertiliser company said.

A senior official with the country's leading co-operative fertiliser company said most of the subsidy reduction would come from potash and phosphate-based fertilisers as import prices have gone down.

India imports all its potash and about 90 percent of its phosphate requirement.

India imported muriate of potash (MoP) at an average price of $490 a tonne in 2011/12, while prices of diammonium phosphate (DAP) hovered around $580 per tonne.